AVS 57th International Symposium & Exhibition
    Plasma Science and Technology Tuesday Sessions
       Session PS-TuP

Paper PS-TuP5
Effect of N2/Ar Flow Rates on Surface Roughness during High Speed Thinning of Si Wafer using F Radicals and NO Gas

Tuesday, October 19, 2010, 6:00 pm, Room Southwest Exhibit Hall

Session: Plasma Science and Technology Poster Session
Presenter: W. Heo, Sungkyunkwan University, Republic of Korea
Authors: W. Heo, Sungkyunkwan University, Republic of Korea
N.-E. Lee, Sungkyunkwan University, Republic of Korea
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In this work, we investigated on evolution of the surface roughness and morphology of thinned Si surface and die strength of thinned Si during high-speed chemical dry thinning of Si wafers ground by chemical mechanical polishing down to 100 mm. The direct injection of NO gas into the reactor during the supply of F radicals from NF3 remote plasmas was very effective in increasing the Si thinning rate above 22.8 mm/min, due to theNO-induced enhancement of the surface reaction,but resulted in the significant roughening of the thinned Si surface. However, the addition of directly-injected N2/Ar gas, together with NO gas, decreased the root mean square (RMS) surface roughness of the thinned Si wafer significantly. Therefore, rough surfaces of mechanically ground Si wafers could be effectively smoothened by adjusting the additive gas flow rates of N2/Ar during chemical dry thinning of the Si thickness larger than 50 mm. We also measured mechanical strength of thinned Si wafer in order to understand the effect of chemical dry thinning on removal of mechanical damage generated during mechanical grinding. Fracture strength of the thinned Si wafers was measured using 3-point bending test and compared. The results indicated that chemical dry thinning with reduced surface roughness and mechanical damage effectively increased the fracture strength of the thinned Si wafer. It is expected that high-speed dry chemical thinning process has possibility of application to ultra-thin Si wafer thinning with controlled surface roughness and mechanical damage removal after mechanical grinding of silicon wafer.